CONTENTS. 
PAGE. 
Introduction 1 
Material on which Edmontosaurus is based 2 
Osteology of Edmontosaurus 5 
Skuil 5 
Mandible 38 
Outer openings of the skull 46 
Brain 51 
Vertebrae 57 
Ribs 61 
Fore limb 63 
The genus Edmontosaurus. 66 
Classification of the Hadrosauridae 67 
Division into three subfamilies 67 
Comparison with related forms 68 
List of principal works cited 77 
Index 79 
Illustrations. 
Figure 1. Rocks of the Edmonton formation, Red Deer river, Alberta 3 
2. Site of the discovery in 1916 of the second skeleton of Edmontosaurus . . 4 
3. Skull of type of Edmontosaurus regalis; left lateral aspect 6 
4. Superior aspect of the same 7 
5. Cranium of paratype of Edmontosaurus regalis] inferior view. 9 
6. Posterior view of the same 11 
7. Anterior view of the same 14 
8. Superior view of the same 18 
9. Right prefrontal of paratype of Edmontosaurus ; viewed from below oblique- 
ly from the rear 22 
10. Right lachrymal of paratype of Edmontosaurus] external, internal, and 
posterior aspects , 23 
11. Right nasal of paratype of Edmontosaurus] internal aspect, obliquely 
from below 24 
12. Left maxillary of paratype of Edmontosaurus: external and internal 
aspects 26 
13. Left maxillary, palatine, pterygoid, and ectopterygoid of paratype of 
Edmontosaurus: external aspect 27 
14. Left jugal of paratype of Edmontosaurus] viewed from within 92 
15. Left quadrato- jugal of paratype of Edmontosaurus: outer and inner 
aspects 30 
16. Left quadrate of paratype of Edmontosaurus] viewed externally obliquely 
from the front, internally obliquely from the rear, with outlines of 
transverse sections 30 
17. Left pterygoid of paratype of Edmontosaurus] external and internal 
aspects 33 
18. Right palatine of paratype of Edmontosaurus] outer and inner aspects. . 35 
19. Left ectopterygoid of paratype of Edmontosaurus] outer and inner aspects 36 
20. Left mandibular ramus of paratype of Edmontosaurus] inner aspect 38 
21. Left dentary of paratype of Edmontosaurus ] inner aspect 39 
22. Right surangular of paratype of Edmontosaurus: external, internal, and 
superior aspects 42 
23. Portion of left articular of paratype of Edmontosaurus] external, anterior, 
and posterior aspects 43 
24. Left splenial of paratype of Edmontosaurus] outer and inner views 44 
25. Right angular of paratype of Edmontosaurus; outer and inner views. ... 45 
26. Brain-case of paratype of Edmontosaurus] right lateral aspect 48 
27. Cast of brain-cavity of paratype of Edmontosaurus] left lateral, superior, 
and inferior aspects 52 
£329— U 
